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K Rasmussen

Publications and source records attributed to K Rasmussen.

At least 271 records · Page 15Linked to original sources
PubMed1989

Solid-phase sample extraction for rapid determination of methylmalonic acid in serum and urine by a stable-isotope-dilution method.

Methylmalonic acid concentrations are increased in serum in vitamin B12 (cobalamin) deficiency. Here I demonstrate the successful use of anion-exchange extraction for improving newly developed analytical procedures and describe well-documented, reliable performance of this method for rapid determination of methylmalonic acid. The sorbent counter ion is formate, and the elution solvent is formic acid. The dicyclohexyl derivative is measured by selected ion monitoring. For serum, the assay curve is linear from 0.026 to 200 mumol/L. The normal reference interval is 0.08 to 0.56 mumol/L. Added methylmalonic acid is accurately quantified. The sensitivity and the precision exceed those of the current method by three orders of magnitude. The total and within-day CVs are 4.6% to 7.9% and 2.6% to 4.7%, respectively. Similar figures were obtained for urine. This convenient method is useful for evaluation of cobalamin deficiency, especially in patients with normal or moderately depressed cobalamin concentrations in serum.

Adult↗
PubMed1988

Estradiol regulation of reactions involved in turnover of the amino acid acceptor terminus of tRNA in the rat uterus.

Estradiol (E2) increases the specific amino acid acceptor activity of rat uterine tRNAs by increasing the proportion of certain tRNAs with intact and functional 3'-CCA acceptor termini. Activities of tRNA nucleotidyltransferase and 3'-exoribonuclease which synthesize and degrade this terminus, respectively, were measured and neither enzyme was modified by hormone treatment. Since cytidine triphosphate (CTP) levels are below reported Km values for nucleotidyltransferase, changes in CTP concentrations may regulate nucleotidyltransferase activity. An E2-induced 3-fold increase was seen in CTP synthetase activity (conversion of uridine triphosphate, UTP, into CTP). Uterine CTP levels in controls are minute (9 nmol/uterus, approx. 90 microM), and are increased 2.5-fold in E2(12 h)-treated rats. The rate of incorporation of [3H]UTP into the 3'-CCA terminus of tRNA was measured as coupled CTP synthetase-nucleotidyltransferase reactions and a 2.5-fold increase in incorporation occurred 8-12 h after E2 treatment. Injection of azaserine, (inhibitor of CTP synthetase) reduced E2-induced increases in CTP levels, CTP synthetase activity, and leucine acceptor activity of tRNAs. These results indicate that E2 regulates CTP levels by modulation of CTP synthetase activity, and that regulation of synthesis and/or repair of the 3'-CCA terminus of tRNA is proportional to E2-induced uterine cytosolic CTP levels.

Animals↗
PubMed1988

Automatic headspace gas chromatographic method for the simultaneous determination of trichloroethylene and metabolites in blood and urine.

Trichloroethylene, trichloroethanol and trichloroacetic acid (TCA) were quantitated in blood and urine by automated headspace gas chromatography using a fused-silica capillary column coated with 3-micron silicone SE-30 and an electron-capture detector. Total trichloroethanol was determined after enzymatic hydrolysis with beta-glucuronidase and analysed together with trichloroethylene and TCA as chloroform, which are produced by decarboxylation. Analytical conditions were developed under which the thermal decomposition of TCA was optimal. The automated headspace gas chromatography is rapid and good precision is possible. Sample preparation is simple and the sensitivity of the procedure (0.02 microgram/ml) makes it suitable to estimate occupational exposure to trichloroethylene and other halocarbons in humans.

Autoanalysis↗
PubMed1988

A genotoxic study of metal workers exposed to trichloroethylene. Sperm parameters and chromosome aberrations in lymphocytes.

Metal workers exposed to trichloroethylene for the degreasing of metals were studied to evaluate the genotoxicity of this exposure. For 15 workers presently exposed to high doses of trichloroethylene there was no difference from unexposed persons with respect to sperm count and morphology, and a small increase of two fluorescent bodies (YFF%) in spermatozoa. In contrast, there was a highly significant increase in frequency of structural aberrations (breaks, gaps, translocation, deletions, inversions) and hyperdiploid cells in cultured lymphocytes from trichloroethylene degreasers. As control groups, physicians from chemically non-exposed surroundings and a concurrently sampled reference from cytogenetic investigations were used. This study indicates positive correlations between exposure to trichloroethylene and somatic chromosome aberrations, whereas no effect on male germ cells could be demonstrated.

Adult↗
PubMed1988

Potency of antipsychotics in reversing the effects of a hallucinogenic drug on locus coeruleus neurons correlates with 5-HT2 binding affinity.

Systemic administration of the phenethylamine hallucinogen 2,5-dimethoxy-4-methylamphetamine (DOM) has previously been shown to decrease spontaneous activity but increase the response to peripheral nerve stimulation of locus coeruleus (LC) neurons in anesthetized rats. Five antipsychotic drugs (spiperone, chlorpromazine, clozapine, haloperidol, and sulpiride) were tested for their ability to antagonize these effects of DOM in the LC. Spiperone, chlorpromazine, clozapine, and haloperidol were able to completely reverse the effects of a standard dose of DOM, while sulpiride was ineffective. The ED100s for reversing the effects of DOM showed a significant correlation only with the previously shown binding affinity for 5-HT2 receptors. These results suggest that certain types of antipsychotic drugs have activity as 5-HT2 antagonists in vivo.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗
PubMed1988

Psychoorganic syndrome from exposure to fluorocarbon 113--an occupational disease?

A cross-sectional clinical study of 99 workers engaged in degreasing with halogenated hydrocarbons has been carried out. Among 23 cleaners from one factory, all at the time using fluorocarbon 113, we found 3 persons with symptoms and signs of psychoorganic syndrome after heavy exposure to fluorocarbon 113 for 2 1/2-4 1/2 years. The possibility of developing psychoorganic syndrome from occupational exposure to fluorocarbon is discussed by presenting these 3 cases.

Aged↗
PubMed1988

Silent hepatitis-B immunization in laboratory technicians.

The present investigation was initiated to assess the demand for vaccination against hepatitis-B in a department of clinical chemistry. One hundred and twenty-eight employees enrolled for the test programme consisting primarily of screening for hepatitis-B antigen (HBsAg) and antibody to hepatitis-B surface antigen (anti-HBs). Surprisingly it was found, that 8 persons out of 58 who had also participated in a screening survey in 1978 had developed anti-HBs. These persons, who had no history of hepatitis, were also positive for antibodies towards the core antigen of hepatitis-B (anti-HBc). A seroconversion rate of 1,53/100/year for this material was calculated. Six persons who had contracted hepatitis-B during an epidemic 14 years previously, presented with very weak anti-HBs reactivity, but were positive for anti-HBc indicating, that anti-HBc was the more stable indicator of past HBV infection. The cost-effectiveness of vaccination against HBV seems disputable compared with other protective measures. The high incidence of silent seroconversion indicates a chronic exposure to virus among the laboratory personnel. Therefore, safety precautions against virus exposure are highly recommended.

Adult↗